"In order to investigate the role of matrix metalloproteinases (MMP) in tumor invasion and metastases, we have focused on the multilevel regulation of these enzymes. Studies have shown that MMP-2 levels are elevated in colorectal, breast, thyroid, ovarian and bladder tumor tissues when compared with adjacent normal tissues. We have identified a cellular activation mechanism which is cell surface associated and specific for pro-MMP-2, and which can be induced by pretreatment with phorbol esters or concanavalin A. This cellular activation mechanism does not affect other members of the collagenase gene family. This activation mechanism appears to require cell surface binding of the gelatinase A enzyme. We have demonstrated that formation of a pro-MMP-2/TIMP-2 complex and subsequent binding to a putative TIMP-2 receptor are important steps in this cellular activation mechanism. Characterization of the kinetics of MMP-2 and TIMP-2 biosynthesis to determine when and where formation of the proenzyme-inhibitor complex occurs suggest that the pro-MMP-2/TIMP-2 complex forms extracellularly from free TIMP-2 and free pro-MMP-2. These results suggest that the pro-MMP-2/TIMP-2 complex is unique in that binding of the inhibitor mediates the cellular activation of this protease. MMP-2 activity on cell surface substrates alters cell attachment and spreading. Identification and characterization of these substrates is progressing. In addition, the protein biochemistry of pro-MMP-2 and TIMP-2 interactions are being studied using mutant recombinant enzymes and plasmon surface resonance (BIAcore) and flourescence polarization. Results have identified a critical interaction between the C-terminal domain of pro-MMP-2 and the C-terminus of TIMP-2. Our production of recombinant, C-terminus of TIMP-2 should allow further exploration of this interaction and identification of strategies to effectively disrupt this interaction."